The objective is to study the interaction of collagenase-isolated adult rat hepatocytes with viruses in order to achieve the two separate but related goals of determining the effect of virus infection and transformation on expression of differentiated liver cell functions, and the influence of a differentiated nonproliferating adult hepatocyte on virus replication. These goals will be achieved using rat hepatocytes transformed with wild type and temperature sensitive mutants of SV40 and herpes simplex virus type 2 (HSV-2)-infected adult hepatocytes, respectively. We have generated SV40 transformed hepatocytes, all of which were 100 percent positive for expression of SV40 tumor (T) antigen, but were diverse in expression of specific liver proteins. We propose to use temperature shift to analyze hepatocytes transformed by an SV40 temperature sensitive mutant for loss and acquisition of liver cell proteins and enzymes in parallel with altered characteristics of transformation and expression of T antigen. We will also study the effects of virus infection as well as transformation on expression of differentiated liver cell functions; in particular, expression of albumin and alpha-fetoprotein. We have also established that HSV-2 infection of adult rat hepatocytes is semipermissive and provides a unique system in which virus DNA was synthesized, virus particles were found in the nucleus, host protein synthesis was decreased, but hepatocyte DNA synthesis was stimulated. We propose to analyze the mechanism by which HSV-2 fails to permissively infect but does stimulate host DNA synthesis in an adult rat hepatocyte. SV40 transformed hepatocytes provide continuous lines of cells expressing liver functions which can be used for gathering insight into eukaryotic cell control. Hepatocytes transformed by a temperature sensitive SV40 mutant may provide us with a mechanism by which differentiation can be reversed simply by altering temperature. The HSV-2 infected adult hepatocyte provides a system in which the effect of a differentiated cell type on replication of a virus which can establish both transformation and latent infections can be analyzed.